EP1692563A2

EP1692563A2 - Device for automatic detection of the index marks of an ophthalmic lens

Info

Publication number: EP1692563A2
Application number: EP04805378A
Authority: EP
Inventors: Fabien Essilor International DIVO; Cédric Essilor International LEMAIRE
Original assignee: Essilor International Compagnie Generale dOptique SA
Current assignee: EssilorLuxottica SA
Priority date: 2003-12-10
Filing date: 2004-11-04
Publication date: 2006-08-23
Anticipated expiration: 2024-11-04
Also published as: US20070115353A1; KR20060132637A; CN100570437C; EP1692563B1; FR2863719B1; CN1890596A; JP5122822B2; FR2863719A1; WO2005066692A2; JP2007514936A; WO2005066692A3; ES2427254T3; US7508502B2

Abstract

The invention relates to a device (100) enabling automatic detection of the index marks of an ophthalmic lens (10), comprising a support (110) which is adapted in such a way as to receive said lens, and, on each side of the support, first means (120) for the illumination of the ophthalmic lens installed on said support, and first means (130) for analysis and acquisition of the light transmitted by the lens. The inventive device also comprises an activatable and deactivatable pattern filter (140) arranged between the first illuminating means and the support.

Description

"Device for automatic detection of landmarks of an ophthalmic lens"

The present invention relates generally to the detection of marks on an ophthalmic lens. It relates more particularly to a detection device comprising a support adapted to receive said lens and, on either side of this support, on the one hand, first means of lighting the ophthalmic lens installed on said support and, d 'secondly, the first means of acquisition and analysis of the light transmitted by said lens. The invention finds a particularly advantageous application in the automatic detection of various characteristics of an ophthalmic lens with progressive addition of power and in particular in the verification of at least one locating characteristic, such as a centering, axis characteristic. , locating the reference points for far vision and near vision, of such a lens mounted on a frame. When mounting a progressive lens on a frame, it is important for the visual comfort of the wearer to ensure the proper positioning of the lens with respect to the eye whose refraction or accommodation defect is corrected. The ophthalmic lens is centered when the reference center of the lens provided at conception and the pupil center of the eye are aligned or, otherwise formulated, when the line of sight passes through the reference center of the lens. Centering therefore results from the bringing together of two geometrical-optical data: the pupil's morphology of the wearer and the position on the lens of the reference center. During its manufacture, any progressive lens is provided with temporary markers in the form of a paint marking and permanent markers in the form of engravings. The provisional marks allow convenient centering of the lens prior to mounting. The permanent marks make it possible to identify, on the patient's frame, the nature of the progressive ophthalmic lens, the value of the addition as well as to verify or restore, after erasing the temporary marks, the exact location of said lens. It is understood that the provisional marks will be deleted by the optician before the handing over the glasses to their client and they can, if necessary, be restored from the permanent engraved marks which remain on the lens. More precisely, as shown in FIG. 10, the provisional markers usually include: - a cross 11 called assembly or centering, materializing the center of the far vision zone intended to be positioned at the center of the wearer's pupil when the wearer this looks infinitely right before him; it makes it possible to position the power progression of the lens 10 in height relative to the eye, so that the wearer easily finds, as expected by the designer of the lens, the corrective power which he needs in far vision , in intermediate vision and in near vision;

- A central point 12 located, depending on the types of lenses, from 2 to 6 mm below the mounting cross 11 and which locates the "optical center" of the lens 10; this "optical center" is conventionally, for a progressive lens, the "prism reference" point where the nominal prismatic power of the lens 10 is measured corresponding to the prescription of the wearer;

- a circle 13 for measuring the far vision power of the lens, located in the upper part of the lens 10, just above the mounting cross 11, and which locates the reference point for far vision ; it is therefore the place where a frontofocometer should be placed to measure the far vision power of the lens 10;

a circle 14 for measuring the near vision power of the lens, located in the lower part of the lens 10 and which surrounds the center or reference point of the near vision area; this center is off-center on the nasal side by 2 to 3 mm and the distance which separates it from the mounting cross 11 constitutes the nominal length of the progression of the lens 10;

- One or more lines 15 identifying the horizontal of the lens 10 and which will be used for centering. As also shown in Figure 10, permanent benchmarks generally include:

- two small circles or signs 16 located on the horizontal of the lens 10 passing through the optical center and systematically located 17 mm on either side of the optical center 12; these engravings make it possible to find the horizontal and vertical centering of the lens; - a sign 17 making it possible to identify the brand and the exact nature of the progressive lens (for example V for Varilux®) which is engraved under the small round or nasal sign;

- a 2 or 3 digit number representing the value of the addition (for example 30 or 300 for an addition of 3.00 D) which is engraved under the small circle or time sign. As a reminder, it will be remembered that, for lenses with multiple focal points having one or more power discontinuity lines, these lines serve as permanent benchmarks. The centering of a progressive lens has two components: one vertical, the other horizontal. Vertical centering allows the power progression of the lens to be positioned in height in front of the eye, so that the latter can easily find, as expected by the lens designer, the corrective power it needs. The power of distance vision correction must be reached on the axis of the primary gaze position and the power of near vision on the axis of gaze when lowering it for near vision. This vertical centering is conventionally carried out by means of the far vision centering cross painted for this purpose on the lens by the manufacturer: it consists in positioning the centering cross of the lens in front of the center of the pupil of the eye of the patient looking endlessly. In practice, the optician measures the height between the bottom of the frame and the center of the wearer's pupil looking horizontally and positions the centering cross of the lens at the measured height. Horizontal centering consists in positioning the progressive lens laterally with respect to the eye so that the wearer can optimally use the far vision, intermediate vision and near vision areas. Physiological studies have shown that the pupillary centers present, in 25% of the cases, a horizontal asymmetry of more than 1 mm compared to the nose and, in 60% of the cases, a vertical deviation of more than 1 mm. It is therefore advantageous to be able to check the centering of each of the two lenses independently of the other and this is why it is preferable to be able to measure the right and left interpupillary half-deviations rather than only the overall interpupillary deviation. All progressive lenses have, by construction, a relative positioning of the far vision and near vision zones, with a nasal decentering of the near vision zone relative to the far vision zone. The horizontal centering of the lens can therefore be carried out either with respect to near vision or with respect to far vision (the most usual case). Centering with respect to far vision consists in measuring the right and left interpupillary half-deviations of the patient looking in far vision, i.e. the distances between the root of the nose and the center of the pupils (or more precisely Comean reflections) of the right eye and the left eye. The far vision mounting crosses of the right lens and the left lens are then positioned at these distances from the median or nasal plane of the frame. The lens being suitably oriented around its optical or central axis, with the horizontal lines (or the engraved circles) aligned along the horizontal of the frame, the near vision area is, by the construction of the lens, suitably off-center on the nasal side by 2 to 3 mm compared to far vision. Centering with respect to near vision, which is more rarely achieved, is carried out in the same way by measuring the interpupillary half-deviations of the patient looking at near vision and by positioning the center of the near vision zone of the left and right lenses at these distances. This second method is of particular interest in the event of asymmetrical convergences between the right eye and the left eye. Various devices are already known, which operate either automatically or manually, to detect the various characteristics of a progressive ophthalmic lens mounted on a frame. The frontofocometer is the optical device which makes it possible to automatically and directly determine the frontal optical powers (spherical, cylindrical, prismatic) of an ophthalmic lens by locating the focal lengths of the lens to be measured, and to locate the optical center of a unifocal lens. Most frontofocom beings operate on the same optical principle, as described in the document “Paraxial Optics” by WF Long, in Visual Optics and Instrumentation, Ed. N. Charman, Macmillan Press, London 1991, pages 418-419. Frontofocom already known can be equipped with a system for marking and holding the unassembled lens (with support fingers or lens clamp) of the type that is marketed under the brand Essilor ACL 60 by the company Visionix or under the brand Essilor CLE 60 by the Japanese company Shin Nippon. The tensiscope is a device, currently entirely manual, which allows the optician to detect and locate the tensions existing in the ophthalmic lenses mounted to verify that each ophthalmic lens is correctly mounted on the frame. The tensions in a mounted ophthalmic lens are due to improper machining of the lens which is too large relative to the circle of the frame which receives it. The lens is then forced into the frame, which generates tensions which can deteriorate it. The principle used in the tensiscope consists in highlighting the birefringence of the lens (the index of the lens is no longer isotropic, but depends on the direction of polarization of the light), this birefringence being linked to the stresses undergone by said lens. To highlight this birefringence, the tensiscope comprises, on the one hand, a homogeneous light source, linearly polarized using a polarizer placed just after the light source, which illuminates the mounted ophthalmic lens, and, d 'on the other hand, a second polarizer disposed after the lens through which the optician looks at the illuminated ophthalmic lens. In the absence of tension, the illuminated ophthalmic lens appears homogeneous to the optician. In the event of tension, the optician sees colored or nuanced fringes appear in said illuminated ophthalmic lens, the fringes being all the more tight in one place that the lens is forced in this place. In view of the colored or nuanced fringes observed, the optician must then evaluate the value of the recovery to be made on said lens so that its mounting on the frame is correct, that is to say without constraint. The device for identifying a progressive power addition lens commonly called “Pal Id” (Progressive addition lens Identification) is a device which makes it possible to locate the permanent marks of a progressive ophthalmic lens made of synthetic material. This device illuminates the ophthalmic lens through a pattern filter to reveal the permanent marks on said lens. Finally, there are drilling templates to be placed on the ophthalmic lens to locate on said lens the place of drilling of the mounting holes of the branches of a frame without a circle. The major drawback of these aforementioned devices, distinct from each other, is that they are all four very bulky. In addition, the tensiscope and the Pal Id operate entirely manually, which makes their use tiresome for the optician. Compared to the aforementioned prior art, the invention proposes a device which makes it possible, with the same acquisition means, to carry out automatically, not only the identification of the permanent marks of an ophthalmic lens, but also to measure one or more other characteristics of the lens, in particular to measure the tensions of the lens induced by its mounting on a frame, to directly determine the front optical power of the lens or to locate the holes of a frame template for glasses with pierced lenses. More particularly, the invention provides a device as defined in the Introduction, characterized in that it comprises, between said first lighting means and said support, a pattern filter which can be activated and deactivated. Other non-limiting and advantageous characteristics of the device according to the invention are as follows: - the first acquisition and analysis means are capable of processing the signal at the output of the activated pattern filter to determine the position of the permanent marks of the ophthalmic lens; - It comprises two polarizing filters, one arranged between said first lighting means and said support, the other arranged between said support and said first acquisition and analysis means; - Said pattern filter is formed by a liquid crystal screen; - The liquid crystal screen also forms said polarizing filter disposed between said first lighting means and said support; - Said first lighting means can be activated and deactivated; - It comprises second activatable and deactivatable lighting means, adapted to light an ophthalmic lens installed on said support in grazing light, said first acquisition and analysis means being able to analyze the light beam transmitted by said lens illuminated in grazing light; - said first acquisition and analysis means comprise a digital camera; - Said first acquisition and analysis means comprise image processing means adapted to process the signal obtained at the output of the camera and means for displaying the processed signal. - Said first acquisition and analysis means comprise between the downstream polarizing filter and the camera an optical system for returning light beams comprising a converging lens and a mirror inclined at 45 °. - It comprises a frontofocometer including on the one hand third illumination means arranged laterally with respect to said first illumination means, and adapted to develop a light beam directed on an ophthalmic lens installed on said support positioned opposite said third means d 'illumination, and, on the other hand, of the second means of acquisition and analysis of the light beam transmitted by said lens installed on said support; - The support is movable in translation along two perpendicular axes. - It includes means for measuring the displacement of the support relative to an initial position; - Said measuring means comprise, for measuring the displacement of said support, incremental encoders or at least one passive pointer which, when illuminated by said first lighting means, forms, in shadow, a tracking image on said first acquisition and analysis means making it possible to determine the position of said support in a fixed frame of reference, and - each passive pointer has an external or internal contour line which is polygonal, circular or cruciform. The description which follows with reference to the appended drawings, given by way of nonlimiting examples, will make it clear what the invention consists of and how it can be implemented. In the accompanying drawings: - Figure 1 is a schematic perspective view of the device according to the invention with its lens support in a first position; - Figure 2 is a schematic perspective view of the device according to the invention with its lens support in a second position; - Figure 3 is a schematic side view showing the main internal components of the device of Figure 1 operating in tensiscope mode; - Figures 4A and 4B are schematic top views of two filters with different patterns for the device according to the invention; - Figure 5 is a schematic side view showing the main internal components of the device of Figure 1 operating in Pal Id mode for ophthalmic lenses of synthetic material; - Figure 6 is a schematic side view showing the main internal components of the device of Figure 1 operating in Pal Id mode for ophthalmic lenses in mineral matter; - Figure 7 is a schematic top view of an embodiment of the support of the device of Figure 1 positioned in the second position; - Figure 8 is a schematic top view of an embodiment of the support of the device of Figure 1 positioned in the first position; - Figure 9 is a schematic perspective view of the support of the device of Figure 1; and - Figure 10 is a schematic top view of an ophthalmic lens with progressive addition of power provided with its temporary and permanent markers. Figures 1 and 2 show a device 100 for automatically detecting various characteristics of an ophthalmic lens 10 provided with marks. Advantageously, this device 100 integrates at least three different functions, namely the “Pal Id” function, the tensiscope function and the frontofocometer function. Thus, in "Pal Id" mode, it automatically checks at least one centering characteristic of an ophthalmic lens with progressive addition of power (synthetic or mineral) mounted on a patient's frame by determining the position of the permanent marks of said lens. In tensiscope mode, it automatically detects and locates the tensions existing in the mounted ophthalmic lenses to verify that each ophthalmic lens is correctly mounted on the frame. In frontofocometer mode, it allows to measure or check the power at a reference point of an ophthalmic lens with progressive addition of power or to locate and measure the powers of a single focal ophthalmic lens. The device 100 comprises a frame 1, forming a housing containing different optical elements, on which is mounted a support 110 adapted to receive a spectacle frame provided with ophthalmic lenses 10. As shown in Figures 3 and 5, the device 100 comprises and on the other side of the support 110, on the one hand, of the first lighting means 120 of the ophthalmic lens 10 installed on the support 110 and, on the other hand, of the first means of acquisition and analysis 130 of the light transmitted by said lens 10. Preferably, said first lighting means 120 can be activated and deactivated. They include a white light source 121 and a diffuser 122 for illuminating the ophthalmic lens 10 with diffuse light. The first acquisition and analysis means 130 here comprise a digital camera 134. They further comprise, between a downstream polarizing filter 150 and the digital camera 134, an optical system for returning light beams comprising a converging lens 131 and a 132 mirror tilted at 45 °. Said first acquisition and analysis means 130 also comprise image processing means (not shown) adapted to process the signal obtained at the output of camera 134 and display means (not shown) of the processed signal. As shown in FIGS. 5 and 6, to exercise the "Pal Id" function on ophthalmic lenses made of synthetic material, the device 100 comprises, between said first lighting means 120 and said support 110, a filter with repeated patterns 140 and regular on and off. This pattern filter 140 is advantageously formed by a liquid crystal screen (LCD). FIGS. 4A and 4B show two filters with 140 different patterns activated, one comprising a screen of black dots on a transparent background, the other a screen of black stripes on a transparent background. The device 100 also comprises two polarizing filters, namely an upstream polarizing filter disposed between said first lighting means 120 and said support 110, and a downstream polarizing filter 150 disposed between said support 110 and said first acquisition and analysis 130. These two polarizing filters associated with the first lighting means 120 and with the first acquisition and analysis means 130 allow the device 100 to exercise the tensiscope function (see FIG. 3). The polarization of the two filters is arranged in a common direction (and not in two perpendicular directions as in a conventional tensiscope with crossed polarizing filters), so as to allow the implementation of the other functions and in particular of the "Pal Id" function. »Without blocking the light by the two filters. It is in fact understood that a combination of crossed filters would block the light in the areas of the lenses devoid of tension, which would be opposed to any other identification or measurement thereon. In addition, this common direction of polarization of the two filters must be substantially identical to the direction of polarization of the lens to be analyzed. Otherwise, the non-stretched areas of the lens would “block” the light in combination with the two filters, which would again prevent any identification or measurement on this lens. In practice, the polarization will therefore generally be horizontal with reference to the configuration of use of the lens. When activated, the pattern filter 140 serves to reveal the permanent marks of the ophthalmic lens 10 made of synthetic material placed on said support 110, interposed between said first lighting means 120 and said first acquisition means and d 'analysis ("Pal Id" function). When deactivated, the liquid crystal screen forming the pattern filter 140 makes it possible to carry out another measurement on said ophthalmic lens 10 since it also forms the upstream polarizing filter disposed between said first lighting means and the lens. (tensiscope function). As shown in FIG. 6, the device 100 furthermore comprises second lighting means 120 ′ which can be activated and deactivated, adapted to illuminate in grazing light an ophthalmic lens 10 ′ made of mineral material installed on said support 110, said first acquisition and analysis means 130 being able to analyze the light beam transmitted by said lens 10 ′ illuminated in grazing light. These second lighting means 120 ′ allow permanent marks to appear on ophthalmic lenses made of mineral material (“Pal Id” function). Of course for this operation, the first lighting means 120 must be deactivated in favor of the second lighting means 120 '. As shown more particularly in FIGS. 3 and 5, in order to exercise the frontofocometer function, the device 100 comprises power measurement means adapted to measure at a reference point the power of the ophthalmic lens 10. In the example proposed, these power measurement means comprise third illumination means 220 disposed laterally with respect to said first illumination means 120, and adapted to develop a light beam directed on an ophthalmic lens installed on said support 110 positioned opposite said third means of illumination 220. It also comprises downstream of a frontofocometer 221 tip including a Hartmann mask, second means of acquisition and analysis 230 of the light beam transmitted by said lens installed on said support 110 opposite said frontofocometre tip 221 These second acquisition and analysis means 230 comprise a camera 231. As the mo ntrent Figures 1 and 2, the support 110 is more particularly adapted to support a spectacle frame M of a patient. To this end, it includes a nose 111 and a clamping jaw 112 able to clamp the spectacle frame M (see FIG. 9). The nose 111 is a half-cylinder which rises from a cylindrical base 11A. The clamping jaw 112 is attached to the cylindrical foot 111A, it comprises an inverted L-shaped part of which a free end comprises a notch 112A facing the nose 111. Thus, the nose of the mount M rests on the cylindrical foot 111 A and is clamped between said notch 112A of the clamping jaw 112 and said nose 111. Advantageously, the clamping jaw 112 is movable in translation relative to said nose 111 while being permanently returned to an initial position relative to the latter by an elastic return means (a spring not shown) so as to guarantee correct tightening of the nose of the M-mount and therefore maintaining said M-mount on said support 110 in a fixed position. More particularly, the clamping jaw 112 comprises a pull which slides in a groove (not shown ) of the cylindrical foot 111A which contains the return spring in position of said jaw. Advantageously, the support 110 is movable in translation in a plane, along two axes X, Y perpendicularly to each other to take different positions for measuring the characteristics of the ophthalmic lens 10 corresponding to the different modes of operation of the device 100 as will be explained more fully below. details later (see Figures 7 and 8). To do this, the nose 111 of the support 110 is attached to a sliding portion 114 capable of sliding in a groove 115A of a strip 115 extending along the axis X and the strip 115 carries rods 116 which extend along the Y axis and which are intended to slide in corresponding conduits (not shown) of the frame 1. Advantageously, said nose 111 attached to said sliding part 114 via the cylindrical foot 111A is able to be moved in translation along the Y axis relative to said strip 115 while being permanently returned to an initial position relative to said strip 115 by an elastic return means (here a spring not shown). This makes it possible to bring the lower edge of the mount M into contact with the corresponding edge 115B of the strip 115. Preferably, said support 110 is displaceable along a third axis Z perpendicular to the first two axes X, Y of displacement. This allows, in frontofocometre mode, to raise the support 110 and therefore the mount M to place one of the ophthalmic lenses 10 then the other in the appropriate measurement position without hitting the frontofocometre 221 tip. In addition, the nose 111 of the support 110 is pivotally mounted on the said sliding portion 114. As shown more particularly in FIG. 9, the cylindrical foot 111A projecting two aligned pins 111 B aligned forming the pivot axis X. These pins 111 B are mounted in grooves formed in two ears 114A provided at the end of said sliding part 114. This pivoting of the nose 111 of the support 110 makes it possible, in frontofocometer mode, to correctly place the corresponding ophthalmic lens 10 relative to the frontofocometer tip 221. So that the device 100 can identify the position of the support 110 in a fixed frame of reference (represented by the frame 1), the latter may include, according to a first embodiment, means for measuring (not shown) its displacement relative to to an initial position. These measurement means include incremental encoders such as for example the incremental encoders manufactured (under the reference RE20F-100-200) by the company COPAL ELECTRONICS. According to a preferred embodiment, said support 110 comprises at least one passive pointer 113; 113 'which, when illuminated by said first lighting means 120, forms, in shadow, a tracking image on said first acquisition and analysis means 130 making it possible to determine the position of said support 110 in the reference frame fixed. As shown in FIGS. 7 and 8, said support 110 being movable between several positions for measuring the characteristics of said lens, it comprises several passive pointers 113, 113 'arranged in such a way that at least one of these passive pointers 1 13, 113 'is illuminated by said first lighting means 120 and forms, in shadow, a tracking image on said first acquisition and analysis means 130, whatever the measurement position taken by said support 110. Each passive pointer 113,113 'has an external or internal contour line 113A, 113A, 113B' polygonal, circular or cruciform. Here, the support 110 comprises, in front of said clamping jaw 112, one of these passive pointers formed by a tongue 113 comprising a lumen 113A with polygonal, circular or cruciform outline. It also comprises behind said strip 115, at the end of said sliding portion 114, another of these passive pointers constituted by a tongue 113 ′ provided with two lights 113 ′ A, 113 ′ B with polygonal, circular or Phillips. Thus, when the device 100 operates in frontofocometer mode on an ophthalmic lens 10 with progressive power addition or on a multifocal lens with power discontinuity, it implements a method for checking the power at a reference point of said lens. comprising the following steps: a) positioning said ophthalmic lens 10 on said support 110, b) moving said support 110 to place the ophthalmic lens 10 opposite the first lighting means 120 (see FIG. 2), c) lighting the ophthalmic lens 10 using said first lighting means 120 while the pattern filter is activated, d) the light transmitted by the ophthalmic lens 10 is collected by the digital camera 134 from said first acquisition and analysis means 130, e) the pattern filter is deactivated, f) the signal is processed leaving said digital camera 134 to determine the position of the permanent marks 16 of the ophthalmic lens 10 (see FIG. 10) in a fixed frame of reference, g) this position is memorized as the initial position of said ophthalmic lens 10, h) we calculate (with the incremental encoders) the movement of said ophthalmic lens 10 relative to said initial position to place said reference point opposite said power measurement means 220,230 (see FIG. 1), i) said support 110 is displaced in accordance with the calculated displacement, and j) the power measurement is carried out at said reference point. When the device 100 operates in “Pal Id” mode, its pattern filter

140 is activated. It can then implement a method for verifying at least one centering characteristic of an ophthalmic lens 10 with progressive power addition, comprising the following steps: a) an initial position of the support 110 is acquired in a fixed reference frame , b) the ophthalmic lens 10 is positioned on the support 110, c) the support 110 is moved to place the ophthalmic lens 10 opposite said first lighting means 120 (see FIG. 2), d) one measures (with the encoders incremental) the movement of the support 110 relative to its initial position, e) the ophthalmic lens 10 is illuminated using said first illumination means 120, f) said digital camera 134 is collected from said first acquisition means and analysis 130 the light transmitted by the ophthalmic lens 10, g) the signal leaving said digital camera 134 is processed to determine the position of the permanent marks 16 of the ophthalmic lens 10 in said fixed frame of reference, and h) the initial position of said support is deduced from the measured displacement of the latter and from the position of the permanent marks of said ophthalmic lens 10, the value of said centering characteristic. The centering characteristics are conventionally the interpupillary half-distance and the mounting height of the ophthalmic lens 10 mounted on its mount M. According to the above-mentioned method, the position of the support 110 is deduced from an initial position determined during the step a) preliminary initialization and a measured displacement of the support 110 to place the ophthalmic lens opposite the lighting means 120 (steps b) to d)). The device 100 can however implement another method for verifying at least one centering characteristic in which the position of the support 110 is acquired by the digital camera 134 using one of these passive pointers 113,113 ′. This method comprises the following steps: a) the ophthalmic lens 10 is positioned on the support 110 placed opposite the activated pattern filter 140, b) the ophthalmic lens 10 is illuminated through said pattern filter 140 using a diffuse light source 121, 122, c) the light transmitted by the ophthalmic lens 10 is collected by the digital camera 134 from the first acquisition and analysis means 130, d) the signal leaving the digital camera 134 is processed to determine the position of the permanent marks of the ophthalmic lens 10 in a fixed frame of reference, e) the position of the support 110 in the fixed frame of reference is determined, f) we deduce from the known position of the support 110 and the position of the permanent marks of the ophthalmic lens 10, the value of said centering characteristic. Advantageously according to this method, during step e) simultaneously carrying out step f) where at least one image of marking formed, in shadow, by a passive pointer 113 provided on the support 110 (see FIG. 7). More specifically, in step b) said support 110 is illuminated using said diffuse light source 121, 122 of said first lighting means 120, in step c) said digital camera 134 is collected by light transmitted through said support 110 and in step f) the signal leaving the digital camera 134 is processed to determine the position of the passive pointer 11A in the fixed reference frame. Of course as a variant, it can be provided that in step e) a signal emitted directly by the support 110 is collected at the level of the fixed mark 113A. Thus according to this method, as shown in FIG. 7, in step f) the interpupillary half-distance is determined by calculating the distance existing between the position of the middle of the nose of said frame M given by one of the passive pointers 113 of said support 1 10 and the position of the central point 12 of said ophthalmic lens 10 located in the middle of the line segment connecting the two permanent reference marks 16 corresponding to said ophthalmic lens 10. According to this method also, in step f) the height is determined in calculating the distance existing between the position of the upper or lower edge of said frame M (materialized by the edge 115A of the strip 115 viewed by the digital camera 134) and the position of the central point 12 of said ophthalmic lens 10 located in the middle of the segment on the right connecting the two permanent reference marks 16 corresponding to said ophthalmic lens 10 (see FIGS. 7 and 10). More generally, the device 100 can implement an automatic detection method for various characteristics of an ophthalmic lens 10 provided with markers, which comprises the following steps: - the ophthalmic lens 10 being placed on said support 110, the support 110 is moved to position said lens in a measurement position, - using said first lighting means, said lens and at least one passive pointer of said support 110 are illuminated, - said acquisition and analysis means are collected 130 a digital file representative of the image of the lens 10, - the pattern filter is deactivated, - A digital file representative of the tracking image formed, in shadow, by said passive pointer, is collected by said acquisition and analysis means 130, - The digital files collected are processed, and - The position of said is deduced therefrom support 110 and that of the marks of the lens in a fixed reference frame. The algorithm which makes it possible to obtain the position of the support from the captured image works as follows: - a binarization of the location image is carried out and only the points of light intensity greater than a threshold are kept predefined, - we perform a segmentation operation: we isolate and number the different objects obtained by binarization (an object is a cluster of contiguous pixels), - we determine the characteristics (size, position of the barycenter) of the different objects, - we sorts the objects according to their size: we delete objects of a size much larger and much smaller than the size of the passive pointer (s), - we compare the remaining objects to the theoretical shape of the passive pointer (s) by performing a correlation between the preserved objects and a mask representative of the passive pointer (s); correlation is a well-known operation in image processing which consists in multiplying the representative mask with the object; the correlation is maximum when the mask and the object are perfectly identical, - we keep the objects for which the correlation is greater than a predefined threshold. At this stage, there normally remains only the objects corresponding to the passive pointer (s), - the position of the passive pointer (s) in the image is determined using the barycenters of the corresponding and previously calculated objects, - deduce the position of the pointers in the fixed frame of reference, because we know the transformation making it possible to pass from a position in pixel in the image to a position in millimeters in the fixed frame of reference, and - we deduce from the position of the passive pointer (s) the position of the support. The transformation allowing to pass from a position in pixel in the image to a position in millimeters in the fixed frame of reference is defined during the calibration of the device. One can for example, to determine this transformation, use a transparent target positioned on the detection device on which a grid of known pitch is screen printed. This target is indexed with respect to the frontofocometer tip, which is the origin of the fixed reference system. Each intersection of the grid corresponds to a well determined pixel and to a well determined coordinate in the fixed frame of reference. We thus have the pixel / coordinate transformation in a fixed reference frame and we store this transformation in memory. Once the device 100 has located the corresponding passive pointer 113 of the support 110 and the permanent marks 16 of the ophthalmic lens 10, it can deduce therefrom the values of the interpupillary half-deviations and of the mounting height of the ophthalmic lens mounted on the mount M. As shown in FIG. 5, the optician can also use the device 100 to simply display the permanent marks of a raw ophthalmic lens in order to mark these marks on said lens with the aid of a marker. When the device 100 operates in tensiscope mode, the pattern filter 140 is deactivated and the LCD screen then forms a polarizing filter. The optician places with the aid of the support 110 the ophthalmic lens mounted on its frame M opposite said first lighting means 120, and more particularly between the two polarizing filters upstream 140 and downstream 150. It illuminates said lens 10 and the digital camera 134 captures the image of the lens 10. Said device 100 can then give one of the following three pieces of information: - binary information indicating that the ophthalmic lens 10 is correctly mounted on its frame M (that is to say without constraint); - binary information indicating that the ophthalmic lens 10 is correctly mounted on its frame M and in the case where the lens is too tight, it indicates to the optician the value of the resumption of machining to be carried out on said lens, and possibly the angular position of the recovery to be effected when it must affect only a portion of the periphery of the lens, so that the mounting of said lens on the frame M is correct, - It displays the captured image of the lens 10 on a screen and the optician can then, at the sight of this image, consider whether the assembly is correct or not, and if necessary decided on the value of the resumption of machining to be carried out on said lens. Finally, advantageously the optician can use the device 100 described above to position and measure on an ophthalmic lens the location and possibly the shape of the holes to be made to mount the arms of a frame without a circle. It places on the support 110 a drilling template and positions said support 110 opposite said first lighting means 120. It illuminates this drilling template and obtains with the digital camera 134 an image of it. The device 100 then displays on a screen the image obtained so that the optician has a simulation of the assembly to be performed. Of course, the information obtained can be sent to a drill (not shown) which automatically makes the holes in said ophthalmic lens at the locations measured. The present invention is in no way limited to the embodiments described and shown, but a person skilled in the art will know how to make any variant which conforms to his spirit.

Claims

CLAIMS 1. Device (100) for automatically detecting marks of an ophthalmic lens (10; 10 '), comprising a support (110) adapted to receive said lens (10; 10') and, on either side of this support (110), on the one hand, the first means of lighting (120) of the ophthalmic lens (10) installed on said support (110) and, on the other hand, of the first means of acquisition and 'analysis (130) of the light transmitted by said lens (10; 10'), characterized in that it comprises, between said first lighting means (120) and said support (110), a pattern filter (140 ) can be activated and deactivated.

2. Device (100) according to claim 1, characterized in that the first acquisition and analysis means (130) are capable of processing the signal at the output of the activated pattern filter to determine the position of the permanent marks of the ophthalmic lens.

3. Device (100) according to one of claims 1 or 2, characterized in that it comprises two polarizing filters, one disposed between said first lighting means (120) and said support (110), the another disposed between said support (110) and said first acquisition and analysis means (130).

4. Device (100) according to one of claims 1 to 3, characterized in that said pattern filter (140) is formed by a liquid crystal screen.

5. Device (100) according to claims 3 and 4, characterized in that the liquid crystal screen (140) also forms said polarizing filter disposed between said first lighting means (120) and said support (110).

6. Device (100) according to one of claims 3 and 5, characterized in that the polarization of the two filters is arranged in a common direction substantially identical to the direction of polarization of the lens to be analyzed.

7. Device (100) according to one of claims 1 to 6, characterized in that said first lighting means (120) can be activated and deactivated.

8. Device (100) according to one of claims 1 to 7, characterized in that it comprises second lighting means (120 ') which can be activated and deactivated, suitable for lighting an ophthalmic lens (10') installed on said support (110) in grazing light, said first acquisition and analysis means (130) being able to analyze the light beam transmitted by said lens (10 ') lit in grazing light.

9. Device (100) according to one of claims 1 to 8, characterized in that said first acquisition and analysis means (130) comprise a digital camera (134).

10. Device (100) according to claim 9, characterized in that said first acquisition and analysis means (130) comprise image processing means adapted to process the signal obtained at the output of the camera (134) and means for displaying the processed signal.

11. Device (100) according to claims 9 and 10, characterized in that said first acquisition and analysis means (130) comprise between the downstream polarizing filter and the camera (134) an optical system for returning light beams comprising a converging lens (131) and a mirror (132) inclined at 45 °.

12. Device (100) according to any one of the preceding claims, characterized in that it comprises a frontofocometer including on the one hand third lighting means (220) disposed laterally with respect to said first lighting means (120 ), and adapted to develop a light beam directed on an ophthalmic lens installed on said support positioned opposite said third illumination means, and, on the other hand, second acquisition and analysis means (230) of the beam light transmitted by said lens installed on said support.

13. Device (100) according to claim 12, characterized in that the support (110) is movable in translation along two perpendicular axes.

14. Device (100) according to claim 13, characterized in that it comprises means for measuring the displacement of the support relative to an initial position.

15. Device (100) according to claim 14, characterized in that said measuring means comprise incremental encoders.

16. Device (100) according to one of 1 to 15, characterized in that said support (110) comprises at least one passive pointer which, when illuminated by said first lighting means (120), forms, in shadow, a tracking image on said first acquisition and analysis means (130) making it possible to determine the position of said support (110) in a fixed reference frame.

17. Device (100) according to claim 16, characterized in that each passive pointer has a polygonal external or internal contour line.

18. Device (100) according to claim 17, characterized in that each passive pointer has a circular external or internal contour line.

19. Device (100) according to claim 17, characterized in that each passive pointer has a cruciform external or internal contour line.